Fishing and resort communities dotting the coastline of four southern American states are bracing for environmental and economic catastrophe from the uncontrolled oil leak in the Gulf of Mexico.
As authorities increased efforts to counter the slick bearing down on sensitive wetlands in Louisiana and Mississippi, as well as sandy beaches as far as Alabama and Florida, at least one expert suggested the leak could already have poured more than 38 million litres of oil into the sea. The Exxon Valdez spill in Alaska in 1989 was about 41 million litres.
With the area's $US2.4 billion-a-year ($2.6 billion) fishing industry brought to a standstill, comparisons were swiftly drawn with the devastating Hurricane Katrina of 2005, the effect of which is still being felt in the wider region.
On the eve of a visit to the region by the President, Barack Obama, the Louisiana Governor, Bobby Jindal, issued a grim prognosis: "This oil spill threatens not only our wetlands and our fisheries, but also our way of life."
Pleasure-boat owners were pulling their craft from the water in anticipation of the slick's arrival some time yesterday. Some communities were building sand banks to prevent the oil from intruding beyond the shore. About 5000 people had been co-opted by the federal government to protect the coast.
But there was a strange disconnect in some areas, too. New Orleans was rocking to a different influx - an extra 100,000 people cramming the Louisiana capital for the final weekend of its spring jazz festival. Weekenders also frolicked along some stretches of beach.
But today is likely to bring a hangover, with a heavier burst of oil expected to be pushed by strong southerly winds into Louisiana's marshlands, an incubator for hundreds of species of birds and animals, including four different types of sea turtles that are due to come ashore to lay their eggs. The wetlands are also a stopover for millions of migrating birds.
The oil leak, which followed an explosion on April 20 that killed 11 men, and later led to the sinking of the BP-owned Deepwater Horizon rig, has forced Mr Obama to suspend politically sensitive plans to expand offshore oil drilling, unveiled last month partly to woo Republican support for climate legislation.
No doubt mindful of the public criticism over the former president George Bush's handling of Katrina, the White House has been at pains to outline its co-ordination effort. It dispatched officials to the region last week.
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The top commander heading the fight, Coast Guard Admiral Thad Allen, who is best known for his effort heading relief efforts after Hurricane Katrina, told reporters the most critical step would be to stop the flow from at least three leaks from the well, which is more than 1.5 kilometres beneath the surface and located about 180 kilometres south-east of New Orleans.
"Any exact estimate is probably impossible at this time,'' Admiral Allen said, adding that the focus would be on stopping the flow at the wellhead as well as on clean-up efforts of the oil.
Ian MacDonald, an oceanographer at Florida State University told the Los Angeles Times: "The size and extent of this slick is 10 million gallons [38 million litres]."
On Thursday the size of the slick was about 3000 square kilometres but by the end of Friday, it had tripled to about 10,000 square kilometres, said Hans Graber, the executive director of the University of Florida's Centre for South-eastern Tropical Advanced Remote Sensing.
"The spill and the spreading is getting so much faster and expanding much quicker than they [originally] estimated,'' Mr Graber said.
Because of the rough weather, traditional clean-up techniques such as skimming oil from the surface of the water and using small boats to position booms to corral it have been put on hold while BP has been trying more experimental techniques.
A BP spokeswoman, Marti Powers, said robot submarines had sprayed a relatively small amount of a dispersant on the oil Friday evening, and observed it working. The chemical breaks oil into particles, which then sink to the ocean floor where it is eaten by various organisms there, Ms Powers said.
Federal and state agencies said more than 84,000 metres of boom had been deployed, with another 96,500 metres available. Almost 24,000 barrels of oil mixed with water had been recovered.